CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Poiseuille flow

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 23, 2006, 14:32
Default Poiseuille flow
  #1
Kirikou
Guest
 
Posts: n/a
It seems to be a very simple question but I'm trying to answer it without results.

While performing the simple case of flow between two plates, my code doesn't work. I found that the problem comes from the boundary conditions. Because I used staggerd grid, I need the value of some fictious value of U and V. I was used to extrapolate but while doing this the continuity equation is not verified. To give you an example :

For U0 = 1 at i=0, i.e. the inflow, this is the two cases I tried :

1st case, I applied the du/dx = 0(u1,j - u-1,j = 0), but obviously d2u/dx2 !=0 (u1,j - 2*u0,j + u-1,j != 0), which is absurd mathematically !!!!!

2nd case, I extrapolate, so d2u/dx2 = 0 but du/dx !=0, it's not absurd but the continuity is not verified on the boundary.

So in the two situation, while computing the pressure boundary condition, we don't obtain dp/dx = 2*(d2u/dy2)/Re, whereas this equation is obtained analyticaly and must be verified.

So where's the problem???? Maybe I miss something but where?????
  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Flow meter Design CD adapco Group Marketing Siemens 3 June 21, 2011 09:33
Boundary condition and Poiseuille flow simulation Cyp OpenFOAM 6 March 11, 2011 15:53
Spectral methods need help - Poiseuille flow vetnav Main CFD Forum 0 February 5, 2010 14:51
Mass flow and U-Mom flow in CFX Zhihua Xie CFX 0 September 3, 2007 10:49
transform navier-stokes eq. to euler-eq. pxyz Main CFD Forum 37 July 7, 2006 09:42


All times are GMT -4. The time now is 12:54.